Method for diagnosing kidney disease comprising detecting the level of annexin a2 or s100a6

ABSTRACT

The present invention provides biomarkers for detecting kidney disease, selected from the oligonucleotide sequence, complementary sequence or derivatives, amino acid sequence or derivatives, fragment, variants, antibody of annexin A2 or S100A6 or combinations thereof. Moreover, the present invention also provides an assay kit and a method for kidney disease detecting, practically for the kidney disease resulting from acute tubular necrosis.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention is related to an innovative method to select acutetubular necrosis-related acute renal failure patient by detectingprotein or nucleotide of annexin A2 and/or S100A6.

2. Description of the Prior Art

Acute tubular necrosis (ATN) is the most common pathologic entityresponsible for the clinical state of acute renal failure (ARF) [1, 2].The two main causes of ATN are ischemic and toxic injuries [3]. In thelatter type, a variety of renal environmental substances that includeheavy metals such as mercury, lead, and uranium are known to cause ARF.Nephrotoxic ATN is histologically evident as epithelial cell necrosis,mainly in the proximal convoluted tubules, with preservation of thetubular basement membrane, and usually intact distal tubular segments[4].

Although severely damaged by toxin, the kidney has the ability tocompletely recover structurally and functionally. Normally, quiescentcells undergo dedifferentiation and regain their potential to divideafter enhancement of DNA synthesis in ATN. Consequent to cellproliferation, the new cells differentiate to restore the functionalintegrity of the nephron [5]. Little is known of the mechanism (s) bywhich regeneration of renal tubules is mediated. The observations thathepatocyte growth factor, epidermal growth factor, and bonemorphogenetic protein-7 are among the potent regulators of kidneyorganogenesis, and that these agents can also promote tubularregeneration after a variety of insults [6], are consistent with theidea that the regeneration process may be partially controlled by amechanism similar to that operating during development. Tubular cellcalcium concentration and content are increased following acute renalinjury induced by ischemic and toxic insults. The divalent calciumcation (Ca²⁺)-signaling system operate by binding to effector molecules,Ca²⁺-binding proteins, that mediate stimulation of numerousCa2+-dependent processes such as transcription and cell proliferation.Two large families of the Ca2+-binding proteins are the annexins and theEF-hand motif S100 proteins [7]. The annexins are a family of 5phospholipids binding proteins that share a common property ofinteracting with membranes and target molecules in a Ca2+-dependentmanner [8, 9]. S100 proteins represent the largest subgroup in theEF-hand Ca²⁺-binding protein family. A unique feature of S100 proteinsis that individual members are localized in specific cellularcompartments from which some are able to relocate upon Ca2+ activation,thus transducing the Ca²⁺ signal in a temporal and spatial manner byinteracting with different targets specific for each S100 protein [10].Interactions between annexins and S100 proteins are now known to includeseveral members of these protein families.

Therefore, it's helpful to search useful biomarkers in annexins and S100protein groups for detecting the reason of acute kidney failure inclinical medical diagnosis.

SUMMARY OF THE INVENTION

To address the problem of detecting acute kidney failure, the presentinvention provides a biomarker for detecting kidney disease, selectedfrom the oligonucleotide sequence, complementary sequence orderivatives, amino acid sequence or derivatives, fragment, variants,antibody of annexin A2 or S100A6 or combinations thereof.

Another object of the present invention is to provide a biomarker fordetecting kidney disease, selected from the oligonucleotide sequence,complementary sequence or derivatives of SEQ ID NO: 1, SEQ ID NO: 11,SEQ ID NO: 3 or SEQ ID NO: 9, amino acid sequence or derivatives,fragment, variants, antibody of SEQ ID NO: 2, SEQ ID NO: 12, SEQ ID NO:4 or SEQ ID NO: 10 or combinations thereof.

Yet another object of the present invention is to provide an assay kitfor kidney disease, comprising biomarkers. The biomarkers are selectedfrom the oligonucleotide sequence, complementary sequence orderivatives, amino acid sequence or derivatives, fragment, variants,antibody of annexin A2 or S100A6 or combinations thereof.

Another object of the present invention is to provide a diagnosis methodfor kidney disease, comprising the following steps: (a) providing asample; (b) providing biomarkers which are selected from:oligonucleotide sequence, complementary sequence or derivatives of SEQID NO: 1, SEQ ID NO: 11, SEQ ID NO: 3 or SEQ ID NO: 9, amino acidsequence or derivatives, fragments, variants, antibody of SEQ ID NO: 2,SEQ ID NO: 12, SEQ ID NO: 4 or SEQ ID NO: 10, or combinations thereof.;(c) contacting said biomarkers in step (b) with the substance of thesample in step (a), the substance is selected from the oligonucleotidesequence, complementary sequence or derivatives, amino acid sequence orderivatives, fragment, variants, antibody of annexin A2 or S100A6 orcombinations thereof; (d) detecting the products of the biomarkersreacting with the substance in step (c).

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 a shows the value of serum creatinine in uranyl-nitrate inducedATN animal model of the example 1.

FIG. 1 b shows the value of serum BUN in uranyl-nitrate induced ATNanimal model of the example 1.

FIG. 1 c shows day 0 of renal tissue sections in uranyl-nitrate inducedATN animal model of the example 1.

FIG. 1 d shows day 3 of renal tissue sections in uranyl-nitrate inducedATN animal model of the example 1.

FIG. 1 e shows day 7 of renal tissue sections in uranyl-nitrate inducedATN animal model of the example 1.

FIG. 1 f shows day 14 of renal tissue sections in uranyl-nitrate inducedATN animal model of the example 1.

FIG. 1 g shows polygon of renal necrosis score in uranyl-nitrate inducedATN animal model of the example 1.

FIG. 1 h shows polygon of renal regeneration score in uranyl-nitrateinduced ATN animal model of the example 1.

FIG. 2 a-d shows immunohistochemical staining of renal section inuranyl-nitrate induced ATN animal model of the example 1. Adedifferentiation marker-anti-vimentin antibody is used.

FIG. 3 a shows gene expression of S100A6, S100A10, S100A11, annexin A1,and annexin A2 with RT-PCR in the example 1.

FIG. 3 b shows relative fold change of S100A6 in uranyl-nitrate inducedATN animal model of the example 1.

FIG. 3 c shows relative fold change of annexin A2 in uranyl-nitrateinduced ATN animal model of the example 1.

FIG. 4 a-h shows expression and renal distribution of S100A6 protein andannexin A2 protein with immunofluorescence staining of S100A6 proteinand annexin A2 protein in uranyl-nitrate induced ATN animal model of theexample 1.

FIG. 4 i shows expression amount of S100A6 protein and annexin A2protein with Western-blot in uranyl-nitrate induced ATN animal model ofthe example 1.

FIG. 5 shows proliferation morphology of renal tube and theco-expression of S100A6 protein and annexin A2 protein with In-situhybridization in uranyl-nitrate induced ATN animal model of the example1.

FIG. 6 shows expression and renal distribution of S100A6 protein andannexin A2 protein in the nephrotoxin model of folic acid induced ATNand rapid acute renal failure model of ischemia-reperfusion injury.

DETAILED DESCRIPTION OF THE INVENTION

One of the objects in the present invention is to provide a biomarkerfor detecting kidney disease, selected from the oligonucleotidesequence, complementary sequence or derivatives, amino acid sequence orderivatives, fragment, variants, antibody or combination of annexin A2or S100A6. The kidney disease is acute renal failure, specifically,resulting from acute tubular necrosis.

Aforesaid oligonucleotide sequence of annexin A2 is selected from SEQ IDNO: 1 or SEQ ID NO: 11.

Aforesaid amino acid sequence of annexin A2 is selected from SEQ ID NO:2 or SEQ ID NO: 12.

Aforesaid oligonucleotide sequence of S100A6 is selected from SEQ ID NO:3 or SEQ ID NO: 9.

Aforesaid amino acid sequence of S100A6 is selected from SEQ ID NO: 4 orSEQ ID NO: 10.

Aforesaid variants of annexin A2 or S100A6 have 80% or more than 80%similarity with the amino acid sequence of annexin A2 or S100A6.

Aforesaid derivatives are to modify the 3′ terminal or 5′ terminal ofsaid oligonucleotide sequence or complementary sequence and keeping 70%or more than 70% similarity with the oligonucleotide sequence of annexinA2 or S100A6. Selectively, the similarity is keeping 90% or more than90%.

Another object of the present invention is to provide a biomarker fordetecting kidney disease, selected from the oligonucleotide sequence,complementary sequence or derivatives of SEQ ID NO: 1, SEQ ID NO: 11,SEQ ID NO: 3 or SEQ ID NO: 9, amino acid sequence or derivatives,fragment, variants, antibody of SEQ ID NO: 2, SEQ ID NO: 12, SEQ ID NO:4 or SEQ ID NO: 10 or combinations thereof. The kidney disease is acuterenal failure, specifically, resulting from acute tubular necrosis.

Aforesaid variants have 80% or more than 80% similarity with the aminoacid sequence of SEQ ID NO: 2, SEQ ID NO: 12, SEQ ID NO: 4 or SEQ ID NO:10.

Aforesaid derivatives of SEQ ID NO: 1, SEQ ID NO: 11, SEQ ID NO: 3 orSEQ ID NO: 9 are to modify the 3′ terminal or 5′terminal of saidoligonucleotide sequence or complementary sequence and keeping 70% ormore than 70% similarity with the oligonucleotide sequence.

Aforesaid derivatives of SEQ ID NO: 1, SEQ ID NO: 11, SEQ ID NO: 3 orSEQ ID NO: 9 are to modify the 3′ terminal or 5′terminal of saidoligonucleotide sequence or complementary sequence and keeping 90% ormore than 90% similarity with the oligonucleotide sequence.

Yet another object of the present invention is to provide an assay kitfor kidney disease, including one or more biomarkers. The biomarkers canbe selected from oligonucleotide sequence, complementary sequence orderivatives, amino acid sequence or derivatives, fragment, variants,antibody of annexin A2 or S100A6. The preceding candidates of annexin A2or S100A6 can be selected in any combination at will. The kidney diseaseis acute renal failure, specifically, resulting from acute tubularnecrosis.

Aforesaid oligonucleotide sequence of annexin A2 is selected from SEQ IDNO: 1 or SEQ ID NO: 11.

Aforesaid amino acid sequence of annexin A2 is selected from SEQ ID NO:2 or SEQ ID NO: 12.

Aforesaid oligonucleotide sequence of S100A6 is selected from SEQ ID NO:3 or SEQ ID NO: 9.

Aforesaid amino acid sequence of S100A6 is selected from SEQ ID NO: 4 orSEQ ID NO: 10.

The kit can comprise secondary antibodies of any amino acid sequence orderivatives, fragment, variants, antibody of annexin A2 or S100A6 orcombinations thereof.

Another object of the present invention is to provide a diagnosis methodfor kidney disease. First, a sample is supplies. Then, biomarkers areprovided, which are selected from: the oligonucleotide sequence,complementary sequence or derivatives, amino acid sequence orderivatives, fragment, variants, antibody of annexin A2 or S100A6 orcombinations thereof. The biomarkers then are contacted with thesubstance of the sample, selecting from the oligonucleotide sequence,complementary sequence or derivatives, amino acid sequence orderivatives, fragment, variants, antibody of annexin A2 or S100A6 orcombinations thereof. Finally, the product of the biomarkers reactingwith the substance is detected by biotechnology. Note should be addedthat the biotechnology can be, for example, but not limit to,enzyme-linked immunosorbent assay (ELISA), radioimmunoassay (RIA),immunofluorescence, reverse-transcription polymerase chain reaction(RT-PCR) or in situ hybridization. Furthermore, the biomarkers can befixed on substrate before contacted with the sample. The substrate isELISA plate or bio-chips.

According to the method of the present invention, one more steps ofrecognizing antibody with secondary antibody can be added beforedetecting the product of the biomarkers reacting with the substance.

Preferably, the substance in the sample can be further labelled byfluorescence prior to contacting with biomarkers.

Aforesaid kidney disease is acute renal failure, specifically, resultingfrom acute tubular necrosis.

The present invention opens the possibilities of utilizingoligonucleotide sequence or amino acid sequence of annexin A2 and/orS100A6 as biomarkers for detecting the type of acute renal failure(especially acute tubular necrosis) and proceeding clinical diagnosisand treatment.

The advantages of the present invention are further depicted with theillustration of examples. The following is a description of theexemplary case of carrying out the platelets provided by the inventionfor bioactivity testing. This exemplary case is not to be taken in alimiting sense, but is made merely for the purpose of furtherillustrating the materials and methods for practicing the presentinvention.

EXAMPLES Animal Models

Urany-Nitrate Induced ATN.

Female 8-week-old C57BL/6 mice were purchased from the NationalLaboratory Animal Breeding and Research Center (Taipei, Taiwan). Allmice received a single tail vein injection of uranyl nitrate((UO2(NO3)2)-6H2O; 100 μg in 100 μL of 5% NaHCO3). The mice weresacrificed at 0, 3, 7 and 14 days after the injection. Blood and urinewere collected for clinical evaluation, and kidneys were removed formolecular and histopathology studies. Samples intended forhistopathology were fixed in formalin according to a standard protocol.

Ischemic Reperfusion Injury.

This model was induced as previously described [11]. Briefly, bilateralischemic reperfusion injury was generated in female Balb/c mice (25-30g) by occluding the renal pedicles with microvascular clamps for 30 minunder ketamine-xylazine anesthesia. Completeness of ischemia wasverified by blanching of the kidneys, signifying the stoppage of bloodflow. The blood flow to the kidneys was reestablished by removal of theclamps (reperfusion) with visual verification of blood return. Micesubjected to sham operation (identical treatment except that the renalpedicles were not clamped) were used as controls. During the procedure,animals were well hydrated and their body temperature maintained with anadjustable heating pad. At 4, 12, 24, and 72 hours post-ischemia, micewere killed, and their kidneys were removed for RNA extraction.

Folic Acid Induced Acute Renal Failure.

Folic acid (240 mg/kg) was administered into female Balb/c mice (25-30g) in vehicle (0.2 ml of 0.3MNaHCO3) or vehicle only by intraperitonealinjection [12]. The control kidneys were analyzed before folic acid orvehicle administration. The mice were sacrificed, and their kidneys werecollected at 1, 3, 7, and 14 days at each time point.

Renal Function

Blood samples collected through the retro-orbital venous plexus werecentrifuged (3000×g, 10 min), and the supernatant containing the serumwas withdrawn and stored at −70° C. until assayed. Renal function wasassessed by measuring the elevation in plasma levels of creatinine andblood urea nitrogen (BUN). These analyses, which utilized Fuji DRI-CHEM3030 (Fuji Photo Film Co. Ltd., Tokyo, Japan), were obtained within 15min once the serum samples thawed.

Renal Histopathology

The formalin-fixed renal tissues were dehydrated in a graded series ofethanol solutions and embedded in paraffin as described elsewhere [13].Three-micron sections were obtained and stained with H&E. For typicallesions of ATN, tubular cell necrosis, of which some of them weresloughed into the tubular lumina accompanied by casts [14].

Quantitative analysis of renal tubular necrosis was performed by opticalmicroscopy. Briefly, 100 intersections were examined for each kidney anda score from 0 to 3 was given for each tubular profile involving anintersection: 0, normal histology; 1, tubular cell swelling, brushborder loss, nuclear condensation, with up to one third of tubularprofile showing nuclear loss; 2, as for score 1, but greater than onethird and less than two thirds of tubular profile shows nuclear loss;and 3, greater than two thirds of tubular profile shows nuclear loss.The total score for each kidney was is calculated by addition of all 100scores with a maximum score of 300. There was also evidence of tubularcell regeneration, it was defined as flattened epithelial cells withhyperchromatic nuclei and mitotic figures [14]. Quantitative analysis ofrenal tubular regeneration was performed by optical microscopy. Briefly,100 intersections were examined for each kidney and a score from 0 to 3was given for each tubular profile involving an intersection: 0, normalhistology; 1, flattened epithelial cells with hyperchromatic nuclei andmitotic figures with up to one third of tubular profile showinghyperchromatic nuclei and mitotic figures; 2, as for score 1, butgreater than one third and less than two thirds of tubular profile showshyperchromatic nuclei and mitotic figures; and 3, greater than twothirds of tubular profile shows hyperchromatic nuclei and mitoticfigures. The total score for each kidney was calculated by addition ofall 100 scores with a maximum score of 300.

Reverse-Transcriptase Polymerase Chain Reaction (RT-PCR)

Total RNA was extracted with Trizol reagent (Invitrogen Corporation,Carlsbad, Calif.) from total kidney. For first strand cDNA synthesis,1.5 μg of total RNA was used in a single-round RT-reaction. The reactionmixture consisted of 0.9 μL Oligo (dT)12-18 primer, 1.0 mM dNTPs, 1×first strand buffer, 0.4 mM DTT, 80 units RNaseout recombinantribonuclease inhibitor, and 300 units of superscript II RNase H(Invitrogen Corporation, Carlsbad, Calif.). PCR was run by using 1 μL ofthe RT reaction mixture as the template, 0.4 μM of gene specificprimers, 1×PC2 buffer, 0.25 mMdNTPs, and 1.5 units of KlenTaq DNApolymerase (Ab Peptides Inc., St. Louis, Mo.). The amplification wascarried out at 94° C. for 2 min, then for 25 cycles at 94° C. for 30sec, 58° C. for 45 sec, and 72° C. for 30 sec, followed by a finalextension at 72° C. for 10 min. The primers were list in table. 1.β-actin and each target gene product were electrophoretically-separatedon a 1% agarose gel and stained with ethidium bromide.

Real-time PCR was performed on an ABI Prism 7700 Sequence DetectionSystem (Applied Biosystems, Foster City, Calif., USA). All of the probesand primers were Assays-on-Demand Gene expression products (AppliedBiosystems). Real-time PCR reactions were using 10 μl of cDNA, 12.5 μlof TaqMan Universal PCR Master Mix (Applied Biosystems), 1.25 μl of thespecific probe/primer mixed in a total volume of 25 μl. The thermalcycler conditions were as follows: 1×2 min 50° C., 1×10 min 95° C., 40cycles denaturation (15 sec, 95° C.) and combined annealing/extension (1min, 60° C.). Amplifications were normalized to β-actin using 2-CTmethod(Applied Biosystems).

Western Blot Analysis

Each sample was run on a 12% SDS-PAGE gel. The gel was electro-blottedonto a nitrocellulose membrane, incubated for 1 h in 20 ml of blockingbuffer (TBS, 5% skim milk), washed three times in TBST, and incubatedwith goat anti-S100a6, goat anti-Anxa2, rabbit anti-PCNA antibodies(Santa Cruz Biotechnology Inc., Santa Cruz, Calif.) at 4° C. overnight.Blots were washed three times and incubated horseradishperoxidase-conjugated rabbit anti-goat or goat anti-rabbit antibodies(Pierce, Ill., USA) for 1 h at room temperature. Membranes were washedthree times, and the membranebound antibody detected was incubatedchemiluminescent reagent plus (PerinElmer Life Sciences, MA, USA) andcaptured on x-ray film.

Immunohistochemical Staining

Immunohistochemical staining was performed on formaldehyde-fixed andparaffin-embedded tissues using the avidin-biotin immunoperoxidasemethod [15]. The antibodies used included goat anti-annexin A2, goatanti-S100A6, rabbit anti-PCNA (Santa Cruz Biotechnology Inc., SantaCruz, Calif.) and goat anti-vimentin (ICN Biomedicals Inc., Irvine,Calif.). Paraffin was removed from sections and followed by rehydration.Endogenous peroxidase activity was quenched and the sections wereblocked with 1% w/v BSA in PBS for 1 hour. The sections were thenincubated with a 1:100 dilution of goat polyclonal anti-S100A6 antibodyin PBS. After incubation with a biotinylated secondary antibody (DAKO,Glostrup, Denmark), the tissue sections were treated with anavidin-biotin-peroxidase complex (DAKO, Glostrup, Denmark). The reactionwas visualized by use of a 3,3′-diaminobenzidine chromogen (DAKO,Glostrup, Denmark) following tissue counterstaining with hematoxylin.For double staining, the slides were incubated with the first antibody,which was demonstrated by the ABC method described above and microwavedwith citrate buffer. Subsequently, the slides were incubated with thesecond antibody for 1 h, which was visualized by an alkaline phosphatasemediated reaction as described previously [16]. Quantitative analysisfor S100A6, annexin A2, and PCNA was performed at high power (200×) byoptical microscopy. Twenty randomly selected cortical fields wereexamined in each section. Preliminary examinations established that therenal tubules were the major portion that was positively stained.

A proportion score and intensity score were assigned. The proportionscore represented the estimated the percentages of positive tubularcells (1=0-20%, 2=20-40%, 3=40-60%, 4=60-80% and 5=80-100%). Theintensity score represented the estimated average staining intensity oftubular cells (0=none, 1=weak, 2=intermediate, 3=strong). The overallamount of positive staining was then expressed as the sum of theproportion and intensity scores.

Immunoelectron Microscopic (IEM) Study

Samples were fixed in a mixture of 4% paraformaldehyde and 0.5%glutaraldehyde in PBS, pH 7.4 and prepared routinely for electronmicroscopy with final embedding in LR White resin as describedpreviously [15]. Ultra-thin sections were cut and placed on nickelgrids. Primary (goat anti-annexin A2; 1:100; Santa Cruz, Calif.) andsecondary antibodies (1:40; gold labeled, British Biocell International,Cardiff, UK) were applied. The presence and localization of the 10 nmgold particles were examined under an electron microscope.

In Situ Hybridization

In brief, 3 μm paraffin sections were mounted on charged glass slidesand stored in airtight boxes at 70° C. Riboprobes were generated byusing a pGEMT-EASY plasmid containing cDNA insert of mouse annexin A2and S100A6 to generate antisense transcripts for in situ hybridization.In vitro transcription was carried out using a commercial kit. For insitu hybridization, Dig-labeled mRNAs were diluted 100-fold inhybridization buffer containing 2 mMEDTA(pH 7.5), 20 mMTris (pH 7.5),0.6 M NaCl, 2×Denhardt's solution, 20% dextran sulfate, 0.1 mg/ml tRNA,and 0.2 M dithiothreitol. After deparaffinization, kidney sections weredigested with 20 μg/ml proteinase K in PBS for 20 mins. Sections wereacetylated using 0.25% acetic anhydride in 0.1M triethanolamine for 10min. A volume of 25-50 μl of hybridization mixture was placed on eachsection and covered with a siliconized glass coverslips.

Hybridization was performed in moist chambers at 42° C. for 16 h.Coverslips were removed by washing in 1× saline sodium citrate (SSC) atroom temperature and 0.2×SSC for 10 min at room temperature. Slides werethen washed in 0.05×SSC for 10 min at room temperature followed by awashing step in 0.025×SSC for 30 min at 37° C.

After rinsing the slides in maleic buffer (0.1M maleic acid, pH 7.5;0.15M NaCl) for 1 min at room temperature and blocking with 1× blockingbuffer 60 mins then incubated with riboprobes (1:200) at 42° C. overnight. Wash with maleic buffer and develop with NBT/BCIP solution indark. With double staining, slides were microwaved with citrate bufferand treated for IHC as reported previously in this article.

Statistical Analysis

All results were expressed as means±standard deviations. Comparisonsbetween two groups were made by unpaired Student's t-test. Differencesamong multiple groups were determined with the one-way ANOVA usingTukey's method for post-hoc analysis. P<0.05 was consideredstatistically different.

Example 1 Detecting ATN with Biomarkers in the Present Invention

In uranyl-nitrate induced ATN animal model, creatinine and BUN (BloodUrea Nitrogen) are measured in different time course. The result areshown in FIG. 1. In mice that received a single dose of uranyl nitrate,the levels of serum creatinine (Cr) rapidly increased to reach1.554±0.371 mg/dL by day 3, as compared to normal controls (0.13±0.03mg/dL) (FIG. 1 a). This difference was significant (p<0.05). Thereafter,Cr levels gradually declined. By day 14 following uranyl nitrateinjection, the Cr levels (0.29±0.19 mg/dL) approached control values(FIG. 1 a). A similar trend and significance (FIG. 1 b) was observed forserum BUN 127.85±11.76 mg/dL on day 3 and 26.53±8.76 mg/dL on day 14,compared to 24.58±1.78 mg/dL in normal controls, p<0.05.

Microscopic examination of renal tissue sections from the mice thatreceived uranyl nitrate showed focal necrosis of renal tubules 3 daysafter injection (FIG. 1 d, g), followed by a more diffuse and intensepattern on day 7 (FIG. 1 e, g). Regeneration of renal tubules was notedon day 7 (FIG. 1 h). On day 14 the histological alterations were mildand had been mostly replaced by regenerating tubules (FIG. 1 f, h) and anormal background (FIG. 1 a). Immunohistochemical staining of renalsection with anti-vimentin, a cellular dedifferention marker, showed theproximal tubular cells undergo cell dedifferentiation to re-enter thecell cycle during the 14 days of disease progression. In normal kidneycells, vimentin expression was restricted to podocytes of glomeruli andfibroblasts in the interstitium (FIG. 2 a). However, the regeneratingtubular cells of the ATN mouse model strongly expressed the vimentinprotein on day 7 (FIG. 2 c). A gradual decline in the protein leveloccurred thereafter and then declined gradually on day 14 (FIG. 2 d).

The expression of genes encoding S100A6, S100A10, S100A11, annexin A2,annexin A1, and annexin A11 was examined by using regular RT-PCRfollowed by quantification by real-time RT-PCR. As shown in FIG. 3,there was an increase of S100A6 and annexin A2 in the progressive ofuranyl-nitrate induced ATN. In contrast, there was no significant changein the expression of S100A10, S100A11, annexin A1 and annexin A11. Theseresults indicate that during the period of dedifferentiation andregeneration in uranyl nitrate-induced ATN, the Ca²⁺-binding proteinsS100A6 and annexin A2 are selectively associated with the induction andrecovery process.

To examine the cellular distribution and association of S100A6 andannexin A2 with ARF, immunohistochemical staining was performed.Paraffin-embedded renal sections from control and from uranyl nitrateinduced-mice kidneys were harvested at timed intervals (0, 3, 7 and 14days) after induction. The expression of S100A6 and annexin A2 resultsindicated that in the kidneys of control animals (day 0), the S100A6(FIG. 4 a) and annexin A2 (FIG. 4 e) are expressed in a very limitednumber of renal tubular epithelial cells (<0.1%). However, theexpression of S100A6 and annexin A2 increased significantly at 7 dayafter induction. At this time point, both the number of the renaltubular epithelial cells expressing S100A6 (FIG. 4 c) and annexin A2(FIG. 4 g) and the intensity of their staining increased significantly.Expression of S100A6 (FIG. 4 b) and annexin A2 (FIG. 4 f) at day 3 wasgreater than that of the control but considerably less than that at day7. S100A6 and annexin A2 staining in kidney sections after day 7indicates considerable variation, with some tubules demonstrating nolabeling in any cell, whereas in some tubules all cells expressed S100A6and annexin A2. The results indicate that S100A6 and annexin A2-positivecells are primarily located in the inner cortical and outer medullaryregions (corticomedullary junction) of the kidney, a region thatcontains the S3 segment of the proximal tubules.

Similarly, the expression of annexin A2 protein in the kidney showed thesame pattern as that of the S100A6, with the intensity of proteinstaining being less than the S100A6 by Western blot analysis (FIG. 4 i).Besides, the expression pattern of these proteins in the kidney sectionswas similar to that of vimentin during the recovery phase.

ATN involves both the loss of epithelial cell polarity and the onset ofproliferative response. Therefore, to determine the relevance of theS100A6 and annexin A2 to these processes, we examined the proliferativestatus of renal tubular epithelial cells and co-expression of these twoproteins. Kidney sections, obtained on day 7 after uranyl nitratetreatment, were double stained with ribo-probes against both S100A6 andannexin A2 mRNA and with the antibody against PCNA, a marker of cellproliferation. The majority of cells (>80%) expressing S100A6 (dark bluecolor—FIG. 5 a) and annexin A2 (dark blue color—FIG. 5 b) and were alsoPCNA positive (red color—FIG. 5).

Semi-quantitative scoring analysis revealed concordant patterns ofabundance among the three proteins (FIG. 5 c). Besides, co-localizationof both S100A6 and annexin A2 was evaluated by double staining. Most ofthe regenerating tubular cells were found to express the proteinssimultaneously (FIG. 5 d).

Example 2 Detecting ATN with Biomarkers in the Present Invention

To determine the general relevance of S100A6 and annexin A2 expressionto the pathophysiology of acute renal failure, we examined theirexpression in two different mouse models. In the nephrotoxin model offolic acid induced acute renal failure, the temporal pattern of S100A6and annexin A2 expression (FIG. 6 a, c) was reminiscent of uranylnitrate model that peaked between day 3 and 7 and returned to normallevel by day 14. The expression of PCNA also peaked between day 3 andday 7 (FIG. 6 e). More importantly, in the rapid acute renal failuremodel of ischemia-reperfusion injury, the expression of S100A6 andannexin A2 (FIG. 6 b, d) were elevated early (12 hours) and declined tonormal level (72 hours) as a respective sensor of tubular injury andrecovery.

During the course of our studies on global gene expression profiling ina mouse model of uranyl nitrate-induced acute renal failure, we observeddramatic up-regulation in the expression of S100A6 (calcyclin) andannexin A2. Accordingly, we postulated these interactive effectormolecules might play a role in the pathophysiology of acute renalfailure and their expression might be useful biomarkers of the temporalevents and processes of the tubular epithelial cell in ATN.

In summary, oligonucleotide sequence and/or amino acid sequence ofannexin A2 and/or S100A6 in the present invention are effectivebiomarkers for detecting ATN-related ARF and deserved to be applied inclinical acute renal failure diagnosis.

Other Embodiments

All features disclosed herein may be combined in any form with othermethods and replaced by other features with identical, equivalent orsimilar purpose. Thus except for the part that is specificallyemphasized, all features disclosed herein constitute only one embodimentamong the numerous equivalent or similar features.

All modifications and alterations to the descriptions disclosed hereinmade by those skilled in the art without departing from the spirits ofthe invention and appended claims shall remain within the protectedscope and claims of the invention.

REFERENCES

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What is claimed is:
 1. A method for diagnosing a kidney disease in asubject, comprising providing a renal sample obtained from a subject,wherein the renal sample is a renal cortical tissue, detecting in therenal sample a level of a biomarker, which is S100A6, and determining,based on the level of the biomarker thus detected, whether the subjectsuffers from a kidney disease, which is acute kidney failure or acutetubular necrosis; wherein an elevated level of the biomarker in thesubject relative to that in a healthy subject indicates that the subjectsuffers from the kidney disease.
 2. The method of claim 1, wherein thedetecting step is performed by examining the protein level of S100A6. 3.The method of claim 2, wherein the protein level of S100A6 is determinedby an immune assay selected from the group consisting of ELISA, WesternBlot, and immunohistochemical staining.
 4. The method of claim 3,wherein the immune assay is ELISA.
 5. The method of claim 3, wherein theimmune assay is Western Blot.
 6. The method of claim 3, wherein theimmune assay is immunohistochemical staining.
 7. The method of claim 1,wherein the detecting step is performed by examining the messenger RNAlevel of S100A6.
 8. The method of claim 7, wherein the RNA level ofS100A6 is determined by real-time PCR.
 9. The method of claim 7, whereinthe RNA level of S100A6 is determined by in situ hybridization.